Various fermentation processes using microorganisms for mass production of useful metabolites, e.g., amino acids, have been used, and furthermore, a variety of techniques including strain development, establishment of fermentation conditions, or the like, have been developed for successful fermentation using the microorganisms. In particular, for the development of a host strain for mass production of useful metabolites, many attempts have been made to induce over-expression or low-expression of a specific gene.
However, in fermentative production using bacteria, the production of useful metabolites may be reduced due to contamination of phages. The contamination of phages is caused mainly due to phage receptors, which are proteins, lipid polysaccharides, or the like, that are capable of attaching phages to a bacterial surface. In the case of Escherichia coli (E. coli), E. coli is attacked by a variety of phages, and accordingly, the study of receptors for each of the phages has been relatively successful. However, the study of the relationship between the phage receptors and the production of L-amino acids has not been sufficiently carried out yet.
In this regard, the inventors of the present invention select genes that are well-known phage receptors, and then, inactivate each of the genes, to reduce the risk of reduction of the L-amino acid production, the risk being considered as a vulnerability of E. coli. Afterwards, the influence on the L-amino acid production is confirmed, and such selection and inactivation of the genes are applied to L-amino acid-producing strains, thereby completing the present invention.